Hexenes hydroformylation

Hydroformylation of Mid Range Olefins - Rhodium/tppts catalysts exhibit low catalytic activity in the hydroformylation of mid range olefins (C5-Cg) in a two phase system due to the much lower solubility of such olefins in water. In the Rh/tppts catalysed biphasic hydroformylation of 1-hexene, for example the conversion is only 11-22% with a n/i ratio of aldehydes of 98/2.353,373 The rate of 1-hexene hydroformylation catalysed by Rh/tppts increased by a factor 2.3 when subjected to ultrasound (35 kHz) and high stirring rates.360,361... 

The cavitron device was used to study the conversion rate of n-l-hexene hydroformylation under biphasic conditions. Under standard reaction conditions, but at a lower pressure of lObar, a conversion of 17% (n/iso ratio 99 1) was reached in this unit compared with 12% in a regular stirred autoclave. 

The structures of anionic, triple-nuclear osmium and iron cluster catalysts supported on copolymers of styrene and divinylbenzene were analyzed by means of IR spectroscopy. Their catalytic activity during 1-hexene hydroformylation [250] and C5H5NO2 carbonylation [251] were investigated. It was found that isomerization proceeds simultaneously in the presence conventional catalysts. In the absence of moisture, a triple-nuclear osmium complex could be removed from a polymeric support after reaction. This suggests catalytic activity for this complex, particularly in the fixed state. Furthermore, a definite correlation was found to exist between polynuclearity and selectivity of heptanol formation. For iron, however, the cluster structure altered during the course of the reaction. 

Pd showed significantly promotional effect than Pt and Ru for Co/Si02 catalyst in hydroformylation of 1-hexene [4], Cobalt free lwt% Ru, Pt and Pd supported on active carbon were prepared and tested in hydroformylation reaction. As shown in Table 1, these kinds of catalysts showed very low activity for 1-hexene hydroformylation. For the Ru catalyst, the 1-hexene eonversion was 81.3%, but the 1-hexene was only converted to isomerization produets. For the Pt and Pd catalysts, both the 1-hexene conversion and oxygenates selectivity were very low. Results show in Table 1 indicate that the noble metal/active carbon catalysts themselves had no catalytic activity of 1-hexene hydroformylation to form oxygenates. 

One interesting design of macromolecular soluble metal complexes is binding of a rhodium complex with sulfonated triphenylphosphine to a soluble polyelectrolyte, polydiallyldimethylammonium tetrakis(3,5-bis(trifluorome-thyl)phenyl borate. In this ease, the content of phosphine groups enables us to control the catalyst solubility in methanol at high content of the phosphine counter ion, the polymer is insoluble and if the ratio of tetraalkylammonium groups to phosphine groups is 4 1 and 10 1, the polymer is soluble in methanol and is an active catalyst of 1-hexene hydroformylation. The catalyst was separated by ultrafiltration [177]. 

A phosphite-modified calixarene with unsubstituted hydroxyl groups was used as a ligand in 1-hexene hydroformylation catalyzed by rhodium complexes [224], The reaction was carried out at a synthesis gas pressure of 6.0 MPa and 160 °C. Rh(acac)(CO)2 was a catalyst precursor. In 3 h, the conversion of the initial alkene virtually reached its theoretically predicted value the yield of aldehydes was 80-85%, and the normal-to-isomeric aldehyde ratio was approximately 1 1. Some similar phosphites 83 were also studied as components of catalytic systems for 1-octene hydroformylation [225]. It was shown that the nature and steric volume of substituent R have no essential effect on the main laws of the process. For example, the conversion was 80-90% at a selectivity with respect to nonanal of about 60% in all cases. The regioselectivity with respect to nonanal was considerably increased to 90-92% by using the chelate biphosphite 84 [220]. 

Table 7. 1-Hexene Hydroformylation with Rigid Diphosphines...

SILP Materials in Liquid-Phase HydroformYlation Reactions 309 Table 15.1 1-Hexene hydroformylation using different reactions systems [7]. 

Several pentacoordinate rhodium-acyl complexes were observed in the phosphorus diamide-modified 1-hexene hydroformylation by using in situ P, and ° Rh NMR spectroscopy. The major rhodium-acyl complex, CH3(CH2)5(C=0)RhL2(C0)2 was found to have a trigonal bipyramidal structure... 

It should be noted that the selectivity to a straight-chain product as well as the rate of 1-hexene hydroformylation was found to be greater for the more basic... 

The hydroformylation of allylic alkenes is characterized, at high temperatures, by competing isomerization [22]. Significant regioselectivity ratios for the hydroformylation of the sole terminal double bond have been obtained by carrying out the reaction at partial substrate conversion, when the starting terminal alkene is still present in excess relative to that resulting from isomerization [22b]. In 1 -hexene hydroformylation the amount of... 

Table 5.2 Comparison of recycling experiments performed under air and inert gas using [Rh(p-Pz)(CO)(TPPTS)]2 as a precatalyst for aqueous 1-hexene hydroformylation [9].

SILP catalysts composed of monophosphines (PPha and TPPTS) dissolved in BMI X (X = Pp6 or BF4) on a l-n-butyl-3-[3-(triethoxysilanyl)propyl]imidazolium-modified silica gel support have been prepared and used in rhodiumhexene hydroformylation [39]. The SILP catalysts were found to have higher activity than analogous biphasic systems however, a significant amount of the metal catalyst leached into the product phase at high conversions (rhodium loss of up to 2.1 mol%), because of the depletion of the ionic liquid phase from the support. Importantly, even at lower conversion, pronounced catalyst deactivation was... 

The effect of argon (280 bar) on the rate of aldehyde formation in 1-hexene hydroformylation catalyzed by Co2(CO)g at 50 °C, 70bar P(CO) and 85 bar P(H2) in toluene was investigated by high-pressure FT-IR spectroscopy. The initial rate of the reaction was found to be reduced by the presence of argon. A similar effect was observed in the RhH(CO)(PPh3)3-catalyzed cydohexene hydroformylation reaction [5]. 

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